The overall objective of this project continues understanding at the molecular level of the interaction the process of signal transduction. FSH receptor will testis by procedures developed during the recent period of project support. The receptor will be partially sequenced to allow preparation of cDNA probes with a view towards cloning of the receptor. Receptor functionality will be confirmed through use of reconstitution experiments. We will utilize enzymic and/or chemical fragmentation of the receptor, together with microsequencing, to identify regions of the receptor required for interaction with FSH. The role of carbohydrates in receptor function will be studied, as will be a possible role of phosphorylation in receptor signal transduction. The significance of the recently observed thioredoxin (protein disulfide isomerase) activity of FSH in terms of receptor activation will be probed, as will a possible function of the FSH receptor as a modulator of calcium ion transport into Sertoli cells (calcium gating effect). In support of the overall program, polyclonal and/or monoclonal antibodies will be raised against the receptor and fragments thereof. A variety of other studies are proposed, directed toward understanding FSH receptor interaction and signal transduction, which will be undertaken as circumstances dictate.